In computer networking, network administrators are often concerned with how to best route traffic flows from one end point to another end point across a network. When provisioning a route for a traffic flow, administrators may implement policies to ensure that certain service functions are applied to the packet or the traffic flow as it traverses across the network. Service functions can provide security, wide area network (WAN) acceleration, and load balancing. These service functions can be implemented at various points in the network infrastructure, such as the wide area network, data center, campus, etc. Network elements providing these service functions are generally referred to as “service nodes.”
Traditionally, service node deployment is dictated by the network topology. For instance, firewalls are usually deployed at the edge of an administrative zone for filtering traffic leaving or entering the particular zone according to a policy for that zone. With the rise of virtual platforms and more agile networks, service node deployment can no longer be bound by the network topology. To enable service nodes to be deployed anywhere on a network, a solution called Service Function Chaining (SFC) Architecture and Network Service Header (NSH) have been provided to encapsulated packets or frames to prescribe service paths for traffic flows through the appropriate service nodes. Specifically, Network Service Headers provide data plane encapsulation that utilizes the network overlay topology used to deliver packets to the requisite services.